This is a application for a Shared Instrumentation Grant to permit purchase of MR-compatible high-density ERP recording systems to permit combined event-related potential (ERP) and magnetic resonance imaging (MRI) experiments. Over the past decade, there have been remarkable breakthroughs in the ability to analyze cognition-related brain activity using functional MRI and high-density ERP recording. fMRI possess high spatial resolution but low temporal resolution. In contrast. ERP possess millisecond level temporal resolution but low spatial resolution. Thus, ERP and fMRI provides complementary information regarding neurophysiological bases of normal and abnormal cognition. NKI currently houses research dedicated 3T and 7T MR systems for human and animal experiments, respectively, along with high-density recording human and animal ERP recording laboratories. Multiple projects are now in progress utilizing parallel MR and ERP recordings, demonstrating convergence between the two methodologies. Clinical projects have demonstrated impaired sensory processing in schizophrenia related to abnormal information processing at the level of primary auditory cortex, and impaired visual ERP generation related to dysfunction of lateral occipital (LO) cortex as well as dorsal stream visual regions. Parallel intracortical recordings in animals have confirmed generator locations and identified underlying neurophysiological mechanisms. ERP and MRI data are presently being acquired in separate sessions in parallel. The proposed equipment would permit ERP data recording during simultaneous MR acquisition. This will greatly enhance efficiency of data acquisition and will substantially decrease variance due to state changes between sessions. The equipment will also permit monitoring of background EEG during both human and animal studies. Software is requested for state-of-the-art ERP dipole mapping and ERP/MRI co-registration.